56s - at a passive table, did I play this too hard?

[Benoit]

A very passive table, a lot of limping and barely any raising pre-flop. I knew I was probably behind on the flop, but I was afraid of a higher flush draw incase it hit. I had seen on multiple occasions them folding to large signs of aggression even when the pot was huge. So 3 betting it was in hopes of folding those higher flush draws.

Was I way off base in how I played this?

0.25/0.50 Hold'em (9 handed) FTR converter on zerodivide.cx

Preflop: Hero is MP2 with 5[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 calls, MP1 calls, Hero calls, <font color="#666666">2 folds</font>, Button calls, <font color="#666666">1 fold</font>, BB checks.

Flop: (6.40 SB) 9[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(6 players)</font>
BB checks, UTG checks, UTG+1 checks, MP1 checks, <font color="#CC3333">Hero bets</font>, Button calls, <font color="#CC3333">BB raises</font>, UTG calls, UTG+1 folds, MP1 folds, <font color="#CC3333">Hero 3-bets</font>, Button folds, BB calls, UTG calls.

Turn: (8.20 BB) 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">BB bets</font>, UTG calls, Hero calls.

River: (11.20 BB) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, BB folds, UTG calls.

Final Pot: 13.20 BB